MAPS and GPS COORDINATES

All maps on "Joe's Guide to Zion National Park" use UTM and NAD27 Datum for coordinate display. While there are several alternate standards and systems, I prefer UTM and NAD27 for two reasons:

1. UTM (Universal Transverse Mercator) is a grid-based coordinate system that is much easier to use than degrees/minutes/seconds (although slightly less accurate). All USGS topo maps of the greater Zion area have the UTM grid (US Zone 12S) drawn in. Each UTM square on the map equals a square kilometer of territory, so it is quite easy to find your location and estimate distances. (Newer versions of the National Geographic Trails Illustrated Map also include the UTM grid.)
2. NAD27 Datum: While NAD83 / WGS84 Datum is more popular in many regions, NAD27 is used by both the USGS topos and the National Geographic Trails Illustrated Map for Zion National Park.

If you use any of the maps on this website to help with navigation, please be sure that your GPS unit is using the same settings! If you accidentally have your GPS set to WGS84 Datum, you will appear to be roughly 200 meters off target.

Note: The history and technical details of coordinate systems are quite complex (and will not be explained here!), but many books and websites give laboriously thorough explanations.

Sample Map:

 

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